1. Technical Field
The disclosure relates to a recording medium onto which information is recorded. Particularly, it relates to a disk-shaped recording medium and a disk cartridge that stores a plurality of disk-shaped recording media in the stack.
2. Background
An optical disk is constituted by a substrate and a cylindrical portion forming a through hole at a center of the substrate. FIG. 15 shows a cross section of a known optical disk, as disclosed in Japanese Utility Model Laid-Open Publication No. H01-103022. A known optical disk has a cylindrical portion at its center and an outer side of the cylindrical portion is cut out. Another known optical disk has a label printing area on one side of the optical disk, as disclosed in Japanese Patent Laid-Open Publication No. H05-198015.